# -*- coding: utf-8 -*-
from PyQt5.QtGui import QSyntaxHighlighter, QColor, QTextCharFormat, QFont
from PyQt5.QtCore import QRegExp

def format(color, style=''):
    """Return a QTextCharFormat with the given attributes.
    """
    _color = QColor()
    _color.setNamedColor(color)

    _format = QTextCharFormat()
    _format.setForeground(_color)
    if 'bold' in style:
        _format.setFontWeight(QFont.Bold)
    if 'italic' in style:
        _format.setFontItalic(True)
 
    return _format

STYLES = {
    'keyword': format('blue'),
    'operator': format('red'),
    'brace': format('darkGray'),
    'defclass': format('black', 'bold'),
    'string': format('magenta'),
    'string2': format('darkMagenta'),
    'comment': format('darkGreen', 'italic'),
    'self': format('black', 'italic'),
    'numbers': format('brown'),
}

class SqlHighLighter(QSyntaxHighlighter):
    # Python keywords
    keywords = [
        'and', 'join', 'left', 'select', 'right', 'in',
        'values', 'update', 'table', 'database', 'null', 'alter',
        'column', 'group', 'where', 'by', 'on', 'between',
        'is', 'from', 'not', 'or', 'order', 'asc',
        'desc', 'insert', 'into', 'set', 'union',
        'all', 'exists', 'like', 'delete', 'create', 'key', 'primary', 'foreign',
        'as', 'view',
    ]

    # Python operators
    operators = [
        '=',
        # Comparison
        '!=', '<', '<=', '>', '>=',
        # Arithmetic
        '\+', '-', '\*', '/', '//', '\%',
        # Bitwise
    ]

    datatypes = [
        'int', 'integer', 'big', 'small', 'varchar', 'char', 'float', 'double', 'date', 'datetime', 'blog'
    ]

    # Python braces
    braces = ['\(', '\)', ]

    def __init__(self, document):
        super(SqlHighLighter, self).__init__(document)
        self.tri_single = (QRegExp("'''"), 1, STYLES['string2'])
        self.tri_double = (QRegExp('"""'), 2, STYLES['string2'])
 
        rules = []
 
        # Keyword, operator, and brace rules
        rules += [(r'\b%s\b' % w, 0, STYLES['keyword'])
            for w in SqlHighLighter.keywords]
        rules += [(r'%s' % o, 0, STYLES['operator'])
            for o in SqlHighLighter.operators]
        rules += [(r'%s' % b, 0, STYLES['brace'])
            for b in SqlHighLighter.braces]
 
        # All other rules
        rules += [
            # 'self'
            (r'\bself\b', 0, STYLES['self']),
 
            # Double-quoted string, possibly containing escape sequences
            (r'"[^"\\]*(\\.[^"\\]*)*"', 0, STYLES['string']),
            # Single-quoted string, possibly containing escape sequences
            (r"'[^'\\]*(\\.[^'\\]*)*'", 0, STYLES['string']),
 
            # 'def' followed by an identifier
            (r'\bdef\b\s*(\w+)', 1, STYLES['defclass']),
            # 'class' followed by an identifier
            (r'\bclass\b\s*(\w+)', 1, STYLES['defclass']),
 
            # From '#' until a newline
            (r'#[^\n]*', 0, STYLES['comment']),
 
            # Numeric literals
            (r'\b[+-]?[0-9]+[lL]?\b', 0, STYLES['numbers']),
            (r'\b[+-]?0[xX][0-9A-Fa-f]+[lL]?\b', 0, STYLES['numbers']),
            (r'\b[+-]?[0-9]+(?:\.[0-9]+)?(?:[eE][+-]?[0-9]+)?\b', 0, STYLES['numbers']),
        ]
 
        # Build a QRegExp for each pattern
        self.rules = [(QRegExp(pat), index, fmt)
            for (pat, index, fmt) in rules]
 
 
    def highlightBlock(self, text):
        """Apply syntax highlighting to the given block of text.
        """
        # Do other syntax formatting
        for expression, nth, format in self.rules:
            index = expression.indexIn(text, 0)
 
            while index >= 0:
                # We actually want the index of the nth match
                index = expression.pos(nth)
                length = len(expression.cap(nth))
                self.setFormat(index, length, format)
                index = expression.indexIn(text, index + length)
 
        self.setCurrentBlockState(0)

        # Do multi-line strings
        in_multiline = self.match_multiline(text, *self.tri_single)
        if not in_multiline:
            in_multiline = self.match_multiline(text, *self.tri_double)


    def match_multiline(self, text, delimiter, in_state, style):
        """Do highlighting of multi-line strings. ``delimiter`` should be a
        ``QRegExp`` for triple-single-quotes or triple-double-quotes, and
        ``in_state`` should be a unique integer to represent the corresponding
        state changes when inside those strings. Returns True if we're still
        inside a multi-line string when this function is finished.
        """
        # If inside triple-single quotes, start at 0
        if self.previousBlockState() == in_state:
            start = 0
            add = 0
        # Otherwise, look for the delimiter on this line
        else:
            start = delimiter.indexIn(text)
            # Move past this match
            add = delimiter.matchedLength()

        # As long as there's a delimiter match on this line...
        while start >= 0:
            # Look for the ending delimiter
            end = delimiter.indexIn(text, start + add)
            # Ending delimiter on this line?
            if end >= add:
                length = end - start + add + delimiter.matchedLength()
                self.setCurrentBlockState(0)
            # No; multi-line string
            else:
                self.setCurrentBlockState(in_state)
                length = text.length() - start + add
            # Apply formatting
            self.setFormat(start, length, style)
            # Look for the next match
            start = delimiter.indexIn(text, start + length)

        # Return True if still inside a multi-line string, False otherwise
        if self.currentBlockState() == in_state:
            return True
        else:
            return False
